Download 2. Sensorineural hearing loss

Presented by
Coleen Maritz
Audiologist
1. Anatomy of the ear
2. Types of Hearing Loss
 Conductive Hearing Loss
- Resultant of outer or middle ear
pathology. When the transmission of
sound is interrupted in the outer ear or
more frequently in the middle ear.
- Children: most common cause is otits
media. Adults: most common cause is
otosclerosis.
Types of Hearing Loss Cont.
 Sensorineural Hearing Loss
- Resultant of inner ear and/or auditory
nerve damage.
- When the hair cells of the cochlea or
the acoustic nerve are damaged.
Types of Hearing Loss Cont.
 Mixed
-
Hearing Loss
Involves a combination of a conductive
and sensorineural hearing loss.
3. Causes of Hearing Loss
 Causes
of Conductive Hearing
Loss
o
Outer and middle ear disorders may
cause a conductive hearing loss.
Outer & Middle Ear Disorders
DISORDERS
DEFINITION
Microtia & Atresia
Congenital
malformations of ear &
external auditory canal.
Microtia-abnormal
smallness of auricle.
Atresia-Absence of
opening of external
auditory meatus.
Excessive ear wax
obstructing ear canal
Impacted Cerum &
Foreign Bodies
Outer & Middle Ear Disorders Cont
DISORDERS
DEFINITION
Tympanic membrane
perforation
Otitis media
Hole in the ear drum
Middle ear infection.
Primary caused by
Eustachian tube
dysfunction. Increased
risk: Craniofacial
anomalies, Down’s
syndrome, allergiescigarette smoke
exposure.
Outer & Middle Ear Disorders Cont
DISORDERS
DEFINITION
Otosclerosis
Disorder of bone growth
that affects the stapes
and the bony labyrinth of
the cochlea. Affects
sound transduction
through middle ear.
Outer & Middle Ear Disorders Cont
DISORDERS
Cholesteatoma
Other Middle ear
Disorders:
Physical trauma
DEFINITION
Pocket that forms in the
ear usually due to Otitis
media. Normal
shedding of epithelium
results in growth of
cholesteatoma. Smells
bad if it should burst.
Gun shot, Blow to
head.
Outer & Middle Ear Disorders Cont
DISORDERS
Baro-trauma
Tumours
Tympanosclerosis
DEFINITION
Sudden change in
atmospheric
pressure (Diver,
aeroplane).
 Neoplasms-Glomus
tumor, often causes
tinnitus as well.
Whitish
plaques on the
tympanic membrane.
Causes of Hearing Loss Cont.
 Causes
of Sensorineural Hearing Loss
1. Prenatal Congenital infections
* CMV – viral infection; type of herpes
virus transmitted in utero; can cause
hearing loss, blindness and seizures
* HIV – affinity for CNS; opportunistic
infections cause hearing loss eg.
Meningitis
* Rubella – viral infection
Causes of Hearing Loss Cont.
* Syphilis – often causes progressive
hearing loss; onset after 2 years of age
* Toxoplasmosis – caused by parasite
infection transmitted through contaminated
food; causes hydrocephalus, mental
retardation and hearing loss
Causes of Hearing Loss Cont.
2. Perinatal Causes





Hypoxia
Birth trauma
Hyperbilirubenemia
Ototoxic medication
Premature infants = increased risk for
hearing loss
Causes of Hearing Loss Cont.
3. Acquired hearing loss





Herpes zoster oticus (Ramsay Hunt
Syndrome) – same virus that causes
chickenpox; can cause hearing loss
Mumps – acute systemic viral disease;
common in childhood over the age of 2 years;
often causes unilateral hearing loss
Measles
Meningitis
Serous labyrinthitis (inflammation of labyrinth)
Causes of Hearing Loss Cont.

Ototoxic medication:
[Oto=ear. Ototoxic=Toxic to the ear]
Ototoxic medications are drugs that have the potential to cause
damage to the inner ear structures which may result in temporary
or permanent hearing loss or an aggravation of an existing
sensorineural hearing loss. Consuming more than one ototoxic
medication at a time increases your risk to develop a
sensorineural hearing loss.
Causes of Hearing Loss Cont.
1. Aminoglycosides (antibiotics):
•
•
•
•
•
•
•
•
•
Amikacin
Gentamycin
Garamycin
Kanamycin
Netilmycin
Tobramycin
Streptomycin
Viomycin
Neomycin
Causes of Hearing Loss Cont.

Aminoglycosides (antibiotics) cont:
These medications are toxic when used intravenously in
serious life threathening situations. The blood levels of these
medications are usually monitored to prevent ototoxicity.
Topical preparations and ear drops containing these antibiotics,
Neomycin, Gentamycin, have not been demonstrated to be
toxic in humans.
Causes of Hearing Loss Cont.
2. Erythromycin (antibiotics):
•
•
•
•
•
EES
Eryc
E-mycin
Ilosone
Pediazole
• Biaxin
• Zithromax
New derivatives of
Erythromycin
Causes of Hearing Loss Cont.

Erythromycin (antibiotics) cont:
These are usually ototoxic when given intravenously in dosages
of 2-4 grams per 24hours, especially if there is underlying kidney
insufficiency. The usual oral dosage of one gram per 24hours is
not toxic. There are no significant reports of ototoxicity with new
Erythromycin derivatives, since they are given orally at lower
dosages.
Causes of Hearing Loss Cont.
3. Vancomycin – Vancocin (antibiotics)
This antibiotic is used in a similar manner as the aminoglycosides;
when given intravenously in serious life-threatening infections. It is
potentially ototoxic. It is usually used together with the
aminoglycosides which enhances the possibility of ototoxicity.
Causes of Hearing Loss Cont.
4. Salicylates (used in treatment of arthritis):
Toxic effects usually appear after consuming an average of 6-8
pills per day. Toxic effects are reversible once medication is
discontinued.
• Acetylsalicylic acid
• Aspirin
Causes of Hearing Loss Cont.
5. Antimalarial medication-Quinine
Derivitaves:
Quinine ingestion can cause a syndrome including tinnitus,
sensorineural hearing loss and vertigo. Recent studies suggest
that quinine impairs outer hair cell mobility. Ototoxic effects are
similar to asprin- reversible once medication is discontinued).
Causes of Hearing Loss Cont.
Antimalarial medication-Quinine Derivitaves
(cont.):
•
•
•
•
•
•
Quinidex (causes tinnitus)
Atrabrine
Plaquenil
Quinine Sulfate
Mefloquine
Chloroquine
Causes of Hearing Loss Cont.
6. Loop diuretics:
These medications are usually ototoxic when given
intravenously for acute kidney failure or acute hypertension.
Rare cases have been reported when these medications are
taken orally in high doses in people with chronic kidney
disease.
• Edecrin (Ethacrynic acid)
• Lasix (Furosemide)
• Bumex (Bumetanide)
Causes of Hearing Loss Cont.
7. Chemotherapeutic Agents:
•
•
•
Ciaplatin
Nitrogen Mustard
Vincristine
These medications are ototoxic when given for treatment of
cancer. The ototoxic effects of these medications are enhanced
in patients who are already taking other ototoxic medications.
Causes of Hearing Loss Cont.
8. Nonsteroidal Anti-Inflammatory Drugs
Toxic effects usually appear after consuming an average of 6-8
pills per day. Toxic effects are usually reversible once
medications are discontinued.
•
•
•
•
•
•
Advil
Aleve
Anaprox
Clinoril
Feldene
Lodine
Motrin
Nalfon
Naprosyn
Nuprin
Poradol
Voltarin
Causes of Hearing Loss Cont.
trauma – temporary or
permanent
 Ménière’s disease – causes vertigo,
hearing loss, tinnitus, pressure in ear; can
be unilateral, fluctuating or progressive
 Presbyacusis – age related sensorineural
hearing loss
 Noise exposure- most common cause of
HL.
 Acoustic
Causes of Hearing Loss Cont.

Noise ExposureDamage risk criteria expressed
as the maximum permissible
noise exposure for a given
duration during a work day.
Duration per
day (in hours)
Sound level
(in dB)
8.0
6.0
4.0
3.0
2.0
1.5
1.0
0.5
0.25
90
92
95
97
100
102
105
110
115 (club)
Causes of Hearing Loss Cont.
Syndromes associated with
Auditory Dysfunction
See handout
4. Prevalence of hearing loss

3/1000 infants are born with congenital severe
bilateral hearing loss
 Additional 3 children acquire hearing loss early
in childhood
 Hearing loss occurs twice as frequently as other
congenital abnormalities screened for in
newborns combined: congenital hypothyroidism;
sickle cell anemia; phenylketonuria;
galactosemia
 Prevalence = 10-20 times higher in NICU
Prevalence of hearing loss cont.
 Prevalence




in general population:
2/1000 = severe-profound HL
5/1000 = moderate-severe HL
8/1000 = mild HL
150/1000 = middle ear infections
 Prevalence
expected to be even higher
with increase in HIV/AIDS infection
5. Tinnitus
1. Definition of tinnitus:



“…hearing a sound that is not related to any
external sound in the environment”
Ringing sound in patient’s ears is generated
by patient’s own body, and is not present in
external environment
Most common types of sounds reported by
patients: ringing, hissing, buzzing, cricket
sounds
Tinnitus cont.
2. Neurophysiological model of
Tinnitus




Stages of tinnitus emergence:
Generation- typically in the periphery
Detection – subcortical centers
Perception and evaluation – cotical areas
Sustained activation of emotional (Limbic)
and autonomic nervous systems
Tinnitus cont.
3. Prevalence of tinnitus
• 17% of general population (44million)
• Clinically significant problems for
approximately 4-5% of the population
4. Impact on patients’ lives
• Ranges from mild irritation to total disability,
and in some cases suicide
Tinnitus cont.
5. Causes
• May be associated with sensorineural
hearing loss (damage to OHC and IHC)
• Ionic imbalance in the cochlea
• Dysfunction of cochlear neurotransmitter
systems
• Central
• Certain medication may cause tinnitus: eg.
antidepressants, benzodiazeptines
• Unknown causes in a lot of cases
Tinnitus cont.
6. Treatment



Unable to suppress tinnitus source – therefore
do not currently have a cure
Tinnitus Retraining Therapy – helps patients
to adapt to noise, and to change their brain’s
perception of the tinnitus; makes use of noise
generators to mask tinnitus
Success rate of 80%
6. Hearing Tests
 1.


 2.


 3.


Audiometry
Puretone
Speech
Immittance Testing
Tympanometry
Acoustic Reflexes
Electrophysiological Testing
Otoacoustic Emissions (OAE)
Auditory Brainstem Response (ABR)
Hearing Tests cont.

1. Audiometry
 1.1 What is audiometry & how does it work?


2 measures: intensity & frequency
Intensity:
• Loudness, measured in dB
• Human ear: 0-120 dB

Frequency:
• Pitch/ tone of sound, measured in Hz
• Human ear: 20-20 000Hz; 125-8000 Hz
Hearing Tests cont.
 Air

conduction audiometry:
Earphones, outer ear, middle ear, inner ear, n.
VIII
 Bone

conduction audiometry:
Bone conductor on mastoid
Hearing Tests cont.
 1.2 Aims




of Audiometry:
Measure degree of HL: minimal, mild,
moderate, severe, profound
Measure site of lesion in hearing mechanism
Determine cause of HL
Determine degree of handicap (how HL
affects patient’s activities of daily life)
Hearing Tests cont.
 1.2 Aims

of Audiometry cont:
Obtain indications for appropriate
therapeutic and educational assistance –
hearing aids; assistive listening devices;
speech-language therapy; school placement
Degree of Hearing Loss
Environmental sounds measured
on audiogram
What is an Audiogram?
 An AUDIOGRAM
is a graphic
representation of a hearing test.
Normal Hearing
7. Types of Hearing LossAudiogram
 1.



Conductive hearing loss
Resultant of external or middle ear pathology
Air conduction abnormal
Bone conduction normal
Conductive Hearing Loss
Types of Hearing LossAudiogram cont.
 2.


Sensorineural hearing loss
Resultant of inner ear and/or auditory nerve
damage
Air conduction and bone conduction equally
abnormal
Sensori-neural Hearing Loss
Types of Hearing LossAudiogram cont.
 3.



Mixed hearing loss
Combination of conductive and sensorineural
hearing loss
Air conduction and bone conduction abnormal
Air conduction worse than bone conduction
(air-bone gap)
Mixed Hearing Loss
Hearing Tests cont.
 2.
Immittance Testing
 2.1



Tympanometry
Test of middle ear functioning
Measures pressure, compliance and volume
of middle ear
Able to determine if middle ear pathology is
present eg. Otitis Media
Hearing Tests cont.
 2.2 Acoustic


Reflex Testing
Measures stapedial muscle reflex (middle ear)
in response to loud stimulus
Able to estimate hearing thresholds in difficult
to test populations, although not always
accurately
Hearing Tests cont.
 3.
Electrophysiological Testing
 3.1 Otoacoustic Emissions (OAE)



measure the integrity of the outer hair cells of
the cochlea
Auditory stimulus is presented to external ear
via a probe
Cochlea produces “echo” in response to
stimulus – measured by probe
Hearing Tests cont.
 Advantages


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


of OAEs
Non-invasive
Simple - quick and easy to administer (also
used in infant hearing screening)
Frequency specific
Objective
Does not require behavioural cooperation
Useful in infants, young children,
neurologically compromised
Hearing Tests cont.
 3.2 Auditory



Brainstem Response (ABR)
Electrophysiological procedure
Based on the brainstem’s response to sound
Soft click stimuli are presented to the ear,
whilst electrodes placed strategically on the
head record the brain’s response to the stimuli
Hearing Tests cont.
 Advantages





of ABR:
Frequency specific
Predicts hearing thresholds
No behavioural response required
Objective
Infants, young children
8. Intervention for Hearing Loss
 Medical
- surgical and/or medicinal treatment
 Hearing aids (HA)
 Implantable Devices
- Cochlear Implant (CI)
- BAHA (Bone anchored hearing aid)
- Vibrant Sound Bridge Device

Cochlear Implant
- Electronic device for adults and children
with a severe to profound hearing loss.
- Unlike HA’s, which merely amplify sound,
a CI bypasses the damaged hair cells
and stimulates the hearing nerve directly.
- Implanted directly in the inner ear or cochlea
and electronically stimulates the nerves via
electrodes.
 BAHA
- Direct bone conduction
- Bypasses conductive element
- Creates direct cochlea stimulation
- Conductive or mixed HL’s
- To close the air-bone gap
 Vibrant
Sound Bridge Device
- Implanted in the middle ear
- Device mechanically vibrates the bones
in the middle ear.
- Moderate to severe SNHL